I believe a lot can be gleaned from OBE writers but not just from their writings directly. Perhaps more of us should try to emulate them. The techniques are widely published. I believe personal experience is the only way forward in the short term. At least until mainstream science wakes up. I had an OBE a couple of years ago; a short but unforgettable experience. I suspect most people wouldn't want to come close enough to physical death to experience an NDE, but an OBE can be experience in good health, albeit after considerable effort. As Robert Monroe would have put it... "turning beliefs into knowns".